Field of the Invention
This invention relates to a method for preparing inorganic oxide-based materials of typically spherical form with controllable particle size, preferably monodispersed within a narrow diameter distribution band, the method consisting basically of forming a uniform finely divided dispersion of a sol of at least one of the oxides of interest in a solvent immiscible with the sol and chosen to allow limited coalescence in an emulsion in it, effecting growth by limited coalescence of the dispersed phase to a predetermined diameter by controlling for this purpose the time of growth of said dispersed phase, then causing gelling of the mixture thus obtained by adding a second solvent, and drying the resultant gel.
The method in question enables inorganic materials, typically oxides or oxide mixtures, to be rapidly and advantageously obtained, these forming a second aspect of the present invention and finding application in all those sectors in which high chemical and thermal stability, monodispersed particle size, spherical form and high porosity and surface area are essential requirements.
Of all possible uses, their application to the catalysis field is of particular importance, in which the materials of the present invention can be used as high-quality catalyst supports, especially in olefin polymerization processes using Ziegler-Natta or Phillips catalysts or in such processes conducted in the gaseous phase.
The materials of the invention can also be conveniently used in the insulation sector, in which a material of very low density, low cost and easily processable can certainly compete with foamed polyurethane. In this respect, a spherical monodispersed granular material is runnable and can be treated in many processes as a liquid.
Lastly, but of no less importance, the materials of the present invention can be applied in the ceramics field, in which precursor quality and particle size control are essential.